The cognitive maps that humans compute as representations of the spatial environment they have visited are rarely even close approximations to what was actually experienced. When we experience the environment we seem to see it all so perfectly, yet rarely are we able to reproduce from memory an exact description of the places visited. Yet these vague, muddled descriptions of the places visited are adequate for many spatial reasoning tasks. But how is such an impoverished representation computed from what is initially delivered by one's senses? And what effect does this representation have on the construction of the cognitive map? W e present one method for computing a vague description of each local space visited. It is derived from the initially accurate description needed for the actions the viewer might perform within the local space. We show the effect of this representation on the structure of the cognitive map.